Sure, here are the completed sentences:
Fifty years ago, there wasn't a shopping mall in my town. There was only one café. There was a museum then. There weren't any buses, but there were trams.
Now, there are lots of cafés. There is a shopping mall, but there isn't a museum. There are buses now, but there aren't any trams.
For number 3, you can write two paragraphs based on these sentences to describe your town fifty years ago and now.